diff --git a/app/services/flavored_markdown.rb b/app/services/flavored_markdown.rb
index 0110954f..781438c9 100644
--- a/app/services/flavored_markdown.rb
+++ b/app/services/flavored_markdown.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class FlavoredMarkdown < Redcarpet::Render::HTML
   include Rails.application.routes.url_helpers
   include SharedMarkers
@@ -7,10 +9,9 @@ class FlavoredMarkdown < Redcarpet::Render::HTML
   end
 
   def wrap_mentions(text)
-    text.gsub! /(^|\s)(@[a-zA-Z0-9_]{1,16})/ do
+    text.gsub(/(^|\s)(@[a-zA-Z0-9_]{1,16})/) do
       "#{$1}[#{$2}](#{show_user_profile_path $2.tr('@', '')})"
     end
-    text
   end
 
   def header(text, _header_level)
diff --git a/app/services/twittered_markdown.rb b/app/services/twittered_markdown.rb
index aeadf428..8787c1b4 100644
--- a/app/services/twittered_markdown.rb
+++ b/app/services/twittered_markdown.rb
@@ -1,12 +1,13 @@
-class TwitteredMarkdown < Redcarpet::Render::StripDown
+# frozen_string_literal: true
 
+class TwitteredMarkdown < Redcarpet::Render::StripDown
   def preprocess(text)
     wrap_mentions(text)
   end
 
   def wrap_mentions(text)
-    text.gsub! /(^|\s)@([a-zA-Z0-9_]{1,16})/ do
-      local_user = User.find_by_screen_name($2)
+    text.gsub(/(^|\s)@([a-zA-Z0-9_]{1,16})/) do
+      local_user = User.find_by(screen_name: $2)
       if local_user.nil?
         "#{$1}#{$2}"
       else
@@ -18,6 +19,5 @@ class TwitteredMarkdown < Redcarpet::Render::StripDown
         end
       end
     end
-    text
   end
 end